Study: Breastfeeding benefits overstated

A new study finds that the benefits of breastfeeding are statistically insignificant and challenges the long-held belief that breast milk is a far superior nutrition source over baby formula.

The study, published in the Social Science & Medicine journal, is noteworthy because it compares siblings who were fed differently, allowing the researchers to control for factors such as a family’s socioeconomic status and a mother’s education that affect a child’s outcome. We know that educated women are more likely to breastfeed than uneducated mothers and so if a study looking at the IQs of breast-fed versus bottle-fed babies doesn’t control for the mother’s education, the results will undoubtedly show that breast-fed babies have higher IQs.

“Many previous studies suffer from selection bias. They either do not or cannot statistically control for factors such as race, age, family income, mother’s employment – things we know that can affect both breast-feeding and health outcomes,” the study’s lead author Cynthia Colen, assistant professor of sociology at The Ohio State University, said in a statement. “Moms with more resources, with higher levels of education and higher levels of income, and more flexibility in their daily schedules are more likely to breast-feed their children and do so for longer periods of time.”

Colen’s study also stands out because it looked at the health and education benefits of feeding practices in infancy for children ages 4 to 14. Most breastfeeding studies don’t look at the effects of breastfeeding beyond age 2.

For the study, Colen and her team analyzed data from 8,273 children with 7,319 of them being siblings and 1,773 being “discordant siblings” where one child was breast-fed and other other was bottle-fed.

The study measured 11 outcomes that are commonly looked at in studies on the effects of breastfeeding: BMI, obesity, asthma, hyperactivity, parental attachment (secure emotional relationships between parents and child) and behavior compliance, as well as scores predicting academic achievement in vocabulary, reading recognition, math ability, intelligence and scholastic competence.

As expected, the analyses of the samples of adults and their children across families suggested that breastfeeding resulted in better outcomes than bottle-feeding in most measures: BMI, hyperactivity, math skills, reading recognition, vocabulary word identification, digit recollection, scholastic competence and obesity.

When researchers restricted the sample to siblings who were fed differently within the same families, scores reflecting breastfeeding’s positive effects on 10 of the 11 indicators of child health and well-being were closer to zero and not statistically significant — meaning any differences could have occurred by chance alone.

The only exception was asthma. In all samples, children who were breast-fed were at higher risk for asthma, which could be a result of data generated by self-reports instead of actual diagnoses.

“Instead of comparing across families we are comparing within families, completely taking into account all of those characteristics – both measured and unmeasured – that differ by family, such as parental education, household income and race/ethnicity,” Colen explained in a statement.

Over the last two decades, the American medical community and the media have touted the benefits of breastfeeding, encouraging mothers across America to nurse their babies. The American Academy of Pediatrics recommends “exclusive breastfeeding for about the first six months of a baby’s life, followed by breastfeeding in combination with the introduction of complementary foods until at least 12 months of age, and continuation of breastfeeding for as long as mutually desired by mother and baby.” Many mothers suffer tremendously from severely cracked nipples and low milk supplies yet they dutifully bend of backwards to meet this requirement.

What’s the takeaway from all this? Colen points out that a lot of time, effort and money are poured into supporting breastfeeding. Maybe the energy would be better spent elsewhere?

“If breastfeeding doesn’t have the impact that we think it will have on long-term childhood outcomes, then even though it is very important in the short-term we really need to focus on other things,” she said. “We need to look at school quality, adequate housing and the type of employment parents have when their kids are growing up.

“We need to take a much more careful look at what happens past that first year of life and understand that breast-feeding might be very difficult, even untenable, for certain groups of women. Rather than placing the blame at their feet, let’s be more realistic about what breast-feeding does and doesn’t do.”